GaAsN and GaInAsN have been grown on As(B)- and Ga(A)-rich I I I I substrates by molecular beam epitaxy using a N plasma cell. Secondary ion mass spectrometry has been used to characterize N incorporation and photoluminescence spectroscopy to study the optical properties of GaAsN- and GaInAsN-GaAs wells. Difference in N incorporation has been found to be dependent on the substrate orientation: (I I I)A > (100) > (I 11) B. As for (10 0), the N content in A- and B-(1 1 1) GaAsN increases while the growth rate decreases. Optical properties of (I I I)A and (I 11)13 oriented quantum wells (QWs) are very sensitive to growth conditions, whose optimum is drastically different from those of (10 0) and from each other. The better orientation appears to be the Ga-rich one, which allows for good luminescence properties to be obtained for GaAsN as well as for GaInAsN/GaAs wells. The strained (I 1 1)13 QWs exhibit peculiar properties that can be assigned to the presence of defects originating from N incorporation. (C) 2002 Published by Elsevier Science Ltd.